1. Technical Field of the Invention
This invention relates to a recording and reproducing method and a recording and reproducing apparatus for an optical disc having a wobble pregroove such as a CD-R, a CD-RW, a DVD+R, a DVD-R, a DVD+RW, and a DVD-RW. Particularly, the recording and reproducing method and apparatus is designed for improving a recording and reproducing quality.
2. Prior Art
In carrying out the recording of information on a CD-R or a CD-RW, a wobble signal is detected from a photo-receiving signal of a return light of a recording laser beam reflected from the optical disc, and a spindle motor control of the optical disc is performed so that that the detected wobble signal has a predetermined wobble frequency. Time information (positional information) is extracted by demodulating an ATIP signal recorded by frequency modulation in the detected wobble signal. Conventionally, to detect a wobble signal (practically, wobble error signal) from a photo-receiving signal of a return light of a recording laser beam, a tracking control is effected by a servo loop having such a low frequency band as to follow an eccentricity of the optical disc while preventing a beam spot of the recording optical beam from tracing the wobbling or meandering of the wobble pregroove. Further, a tracking actuator has a resonance frequency of second order due to its mechanical structure in the order of 8 through 9 kHz, which is lower than a wobbling frequency of 22.05 kHz in case of 1× velocity recording. It is necessary to set the servo band of the tracking control to a relatively low frequency in order to remove the resonance frequency of the second order. Thus, in the conventional recording method, the servo band of the tracking control is set to a relatively low frequency range. Consequently as shown in FIG. 2, a beam spot 12 of the recording optical beam travels along a mean center 10b of meandering of a wobble pregroove 10 on an optical disc recording surface. Thereby, pits 14 are recorded along the mean center 10b of meandering of the wobble pregroove 10.
For an example of the conventional art literature disclosing that pits are recorded along a mean center of meandering of a wobble pregroove by controlling a recording beam spot to follow the mean center of the meandering of the wobble pregroove, there is known the following Patent literature 1.
Patent literature 1 is Japanese Unexamined Patent Publication (Kokai) No. 5-101397
In the conventional recording and reproducing method, the pits 14 are formed significantly off the meandering center 10a of the wobble pregroove 10 and thereby overlapping with a side wall face 10c of the wobble pregroove 10 in places where the meandering center 10a of the wobble pregroove 10 is deviated apart from the mean center 10b of the meandering, thereby causing a problem of deteriorating a recording quality and consequently deteriorating a reproduction quality of the recorded information such as jitter and C1 error.